83' 115 hp Mariner 6cyl. No power under load, Water Jacket Cover?

[Mark Nagel]

I have an 83' 115 hp Mariner 6 cyl outboard. It ran perfectly 5 years ago when i stored it. Now it starts one first crank revs up on land, but in the water it bogs and can't rev up (no power). I drained and replaced the gas, rebuilt the fuel pump and carbs, good spark, good compression (120-125psi). The local shop suggested it might be the baffle plate/exhaust manifold. That looked good, but ther was a lot of water mixed with the oil/soot on the motor side of the baffer, but no cracks or leaks I could see.

The Water Jacket cover (on the block under the baffle) looks like there could be a chip out of the bottom corner, but I don't know what it should look like. Could this be the problem? Anyone have a detailed picture of one of these?


Any other ideas? I'm on the verge of cutting my losses and scrapping it.

Thanks,

Mark Nagel

 

[rtpassini]

Re: 83' 115 hp Mariner 6cyl. No power under load, Water Jacket Cover?

im a noob...

but if it has good compression, how can it have no power under load?

can you do leakdown tests on boat motors?

 

[Chris1956]

Re: 83' 115 hp Mariner 6cyl. No power under load, Water Jacket Cover?

Mark, Look at the spark plugs. If they look brand new, they may be getting steam cleaned by water infiltration.

Are the carbs cleaned and adjusted correctly? Does the stator high speed windings ohm out properly?

 

[Mark Nagel]

Re: 83' 115 hp Mariner 6cyl. No power under load, Water Jacket Cover?

Carbs are good, I might do the link and sync in the FAQ. Who do I do the high speed winding test?

Yes, the plugs do look new. WHat does the steam cleaning point to?

Mark

 

[Chris1956]

Re: 83' 115 hp Mariner 6cyl. No power under load, Water Jacket Cover?

Steam cleaned plugs means water infiltration. Water puts out the fire, which is not good. Water get into those old Mercs via the lower crankshaft seals, exhaust cover leaks, baffle plate leaks or inner exhaust cover leaks. which spark plug is exceptionally clean?

CDI Electronics website has tests for the stator windings.

 

[Mark Nagel]

Re: 83' 115 hp Mariner 6cyl. No power under load, Water Jacket Cover?

Thanks, I was wrong, I talked to my friend doing the work, the plugs were not steam cleaned. He said clean, he meant normal. I ordered new gaskets for the baffle plate and water jacket cover. Once together I'll recheck the electrics including the stator. Any other ideas?

Mark

 

[Chris1956]

Re: 83' 115 hp Mariner 6cyl. No power under load, Water Jacket Cover?

Mark, Make sure you have spark on all the plugs. if you got good spark, good compression and no water, it should develop power....